By the color development of a color photographic light-sensitive material, after exposure, an oxidized aromatic primary amine developing agent is reacted with a coupler to form a dye, thus, a color image is formed. In this system, a subtractive method is generally used for color reproduction. In accordance with such a system blue, green and red colors are reproduced by forming yellow, magenta and cyan color images which are in complimentary relation thereto, respectively. In general, acylacetamide or dibenzoylmethane type couplers are employed for forming yellow or color images, pyrazolone, cyanoacetyl or indazolone type couplers are used for forming magenta color images, and phenol type couplers, for example, phenols and naphthols, are utilized for forming cyan color images.
To produce color photographs, couplers which form dyes are incorporated into a developer or are present in light-sensitive photographic emulsion layer(s). A variety of 5-pyrazolone type couplers for forming magenta color images are known. Known substituents at the 3-position of the 5-pyrazolone ring include an alkyl group, an aryl group, the alkoxy groups as described in U.S. Pat. No. 2,439,098, the acylamino groups as described in U.S. Pat. Nos. 2,369,489 and 2,600,788, and the ureido groups as described in U.S. Pat. No. 3,558,319 and an anilino group. 3-Anilino-5-pyrazolone type couplers have often been described in the art since U.S. Pat. No. 2,311,081 (U.S. Pat. No. Re. 22,329) was issued and several improvements have been proposed. British Pat. No. 956,261 discloses that azomethine dyes obtained from derivatives in which the ortho position of the anilino group is substituted with an alkoxy group or a halogen atom have advantageous spectral absorption for color photography in that undesired absorption in the red light region is particularly low.
Specific examples of diffusion resistant couplers which belong to this type and are capable of being incorporated into photographic emulsions are described in U.S. Pat. Nos. 3,930,861, 3,907,571, 3,928,044 and 3,935,015, etc.
These couplers have the characteristics that the undesired absorption of magenta azomethine dyes obtained upon color formation using the same in the red light region is low, the cut off the main absorption is good at the longer wavelength side, and magenta color images having a high color density are obtained because the coloration speed is high. Furthermore, their solubility in organic solvents having a high boiling point is improved so that, after dissolving these couplers in organic solvents, the couplers are emulsion dispersed in an aqueous medium in the form of colloidal particles and then added to emulsions. However, these couplers have the disadvantages that the degree of yellow staining at the unexposed portion after color development processing is high and this degree of yellow staining is increased upon irradiation with light. These disadvantages are particularly serious for color light-sensitive material such as color printing papers, etc. which are irradiated with actinic rays for a long period of time.
In order to eliminate these disadvantages, it has been proposed that the structure of the coupler per se is appropriately selected thereby improving the light fastness. On the other hand, many methods for improving the light fastness using various additives have also been proposed. For example, methods in which a compound such as an ultraviolet radiation absorbing agent, a hydroquinone derivative, a phenol derivative, or tocopherol, etc. is employed are known. Further, a compound in which the hydroxy group in the above described hydroquinone derivative, phenol derivative or chroman derivative such as tocopherol is substituted with an alkoxy group, an acyloxy group, etc. is recently proposed for the purpose. However, these methods using such additives have a limit. For example, a relatively large amount of the compound must be added to obtain sufficient light fastness which is frequently accompanied with various disadvantages, for examples, coloration, change in color hue, formation of fog, etc. due to the compound added.